Radio communication devices, such as two-way portable radios, rely on good antenna performance for reliable communications. Such devices are often used by public-safety agencies such as police departments, fire departments, emergency medical responders, and the military to name a few. There is an increased interest in the public-safety arena for portable two-way radios equipped with antenna structures that enable operation over multiple communication frequency bands to enhance interoperability amongst the different public-safety agencies. Typically, antenna structures are either internal or external to the radio housing. While separate external antenna structures may be used to cover multiple frequency bands or achieve other functional benefits (e.g., receive diversity, radiation pattern beam steering, to name a few), the use of multiple separate external antenna structures is impractical in view of the size constraints of the portable devices as well as the encumbrance associated with increased device height potentially associated with multiple external antenna structures. Portable communication devices incorporating prohibitively large, lengthy and/or stiff external antenna structures can be cumbersome for a user to wear on the body and are also susceptible to breakage under extreme use condition in mission-critical public-safety settings. Hence, there is a need to provide single- and multi-band operation without significantly increasing the size of the overall device or negatively impacting performance. Challenges associated with the design of single- and multi-band antenna configurations include, but are not limited to, operational bandwidth, efficiency of operation, and size constraints.
Accordingly, there is a need for an improved antenna for portable radio applications.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.